A method and system to improve electrophotographic run cost makes an active adjustment of charge device actuator settings based on various conditions and states of an image forming apparatus.
Image forming apparatus, such as a xerographic reproduction apparatus, use a photoconductor in the form of a drum or a belt in the creation of electrostatic images upon which toner is deposited and then transferred to another electrostatically charged belt or drum, or to paper or other media. Once the toner image is transferred, most xerographic apparatus clean the photoconductor.
The life of the photoconductor in a xerographic print engine is typically limited by the eventual occurrence of some form of print quality defect related to the photoconductor. One of the typical failure mechanisms is the slow wearing away of the surface layer of the photoconductor. For example, the thickness of the photoconductor will decrease through use over time, typically through contact friction with various other devices in the system (e.g., the transfer roller). Certain types of charging devices, such as AC-biased charging rolls (BCRs) are known to accelerate the wear rate of the photoconductor surface. The more cycles the photoconductor makes with the AC BCR operating at its high AC bias, the faster the photoconductor will wear. Because of the nature of the photoconductor, a change in its thickness will result in a change in its electrostatic performance. Eventually, after enough of the surface layer has been worn away, print quality defects begin to appear in the customer's prints. An example of this type of defect is the charge depleted spots defect that appears in certain print engines after approximately 10-12 um of the photoconductor outer layer (charge transport layer) has been worn away.